Add flies (doomed #112) from the Hexen retail beta

...because it brought back memories of adding Strife support.
- The search function is radically different, but the flying mechanics are
  the same.

src/CMakeLists.txt

@@ -741,6 +741,7 @@ set( NOT_COMPILED_SOURCE_FILES
 	g_hexen/a_fighterquietus.cpp
 	g_hexen/a_firedemon.cpp
 	g_hexen/a_flechette.cpp
+	g_hexen/a_flies.cpp
 	g_hexen/a_fog.cpp
 	g_hexen/a_healingradius.cpp
 	g_hexen/a_heresiarch.cpp

src/actor.h

@@ -1035,7 +1035,7 @@ public:
 	virtual bool UpdateWaterLevel (fixed_t oldz, bool splash=true);
 	bool isFast();
 	bool isSlow();
-	void SetIdle();
+	void SetIdle(bool nofunction=false);
 	void ClearCounters();
 	FState *GetRaiseState();
 	void Revive();

src/g_hexen/a_flies.cpp

@@ -0,0 +1,106 @@
+static FRandom pr_fly("GetOffMeFly");
+
+//===========================================================================
+//
+// FindCorpse
+//
+// Finds a corpse to buzz around. We can't use a blockmap check because
+// corpses generally aren't linked into the blockmap.
+//
+//===========================================================================
+
+static AActor *FindCorpse(AActor *fly, sector_t *sec, int recurselimit)
+{
+	AActor *fallback = NULL;
+	sec->validcount = validcount;
+
+	// Search the current sector
+	for (AActor *check = sec->thinglist; check != NULL; check = check->snext)
+	{
+		if (check == fly)
+			continue;
+		if (!(check->flags & MF_CORPSE))
+			continue;
+		if (!P_CheckSight(fly, check))
+			continue;
+		fallback = check;
+		if (pr_fly(2))	// 50% chance to try to pick a different corpse
+			continue;
+		return check;
+	}
+	if (--recurselimit <= 0 || (fallback != NULL && pr_fly(2)))
+	{
+		return fallback;
+	}
+	// Try neighboring sectors
+	for (int i = 0; i < sec->linecount; ++i)
+	{
+		line_t *line = sec->lines[i];
+		sector_t *sec2 = (line->frontsector == sec) ? line->backsector : line->frontsector;
+		if (sec2 != NULL && sec2->validcount != validcount)
+		{
+			AActor *neighbor = FindCorpse(fly, sec2, recurselimit);
+			if (neighbor != NULL)
+			{
+				return neighbor;
+			}
+		}
+	}
+	return fallback;
+}
+
+DEFINE_ACTION_FUNCTION(AActor, A_FlySearch)
+{
+	// The version from the retail beta is not so great for general use:
+	// 1. Pick one of the first fifty thinkers at random.
+	// 2. Starting from that thinker, find one that is an actor, not itself,
+	//    and within sight. Give up after 100 sequential thinkers.
+	// It's effectively useless if there are more than 150 thinkers on a map.
+	//
+	// So search the sectors instead. We can't potentially find something all
+	// the way on the other side of the map and we can't find invisible corpses,
+	// but at least we aren't crippled on maps with lots of stuff going on.
+	validcount++;
+	AActor *other = FindCorpse(self, self->Sector, 5);
+	if (other != NULL)
+	{
+		self->target = other;
+		self->SetState(self->FindState("Buzz"));
+	}
+}
+
+DEFINE_ACTION_FUNCTION(AActor, A_FlyBuzz)
+{
+	AActor *targ = self->target;
+
+	if (targ == NULL || !(targ->flags & MF_CORPSE) || pr_fly() < 5)
+	{
+		self->SetIdle();
+		return;
+	}
+
+	angle_t ang = R_PointToAngle2(self->x, self->y, targ->x, targ->y);
+	self->angle = ang;
+	self->args[0]++;
+	ang >>= ANGLETOFINESHIFT;
+	if (!P_TryMove(self, self->x + 6 * finecosine[ang], self->y + 6 * finesine[ang], true))
+	{
+		self->SetIdle(true);
+		return;
+	}
+	if (self->args[0] & 2)
+	{
+		self->velx += (pr_fly() - 128) << BOBTOFINESHIFT;
+		self->vely += (pr_fly() - 128) << BOBTOFINESHIFT;
+	}
+	int zrand = pr_fly();
+	if (targ->z + 5*FRACUNIT < self->z && zrand > 150)
+	{
+		zrand = -zrand;
+	}
+	self->velz = zrand << BOBTOFINESHIFT;
+	if (pr_fly() < 40)
+	{
+		S_Sound(self, CHAN_VOICE, self->ActiveSound, 0.5f, ATTN_STATIC);
+	}
+}

src/g_hexen/a_hexenmisc.cpp

@@ -38,6 +38,7 @@
 #include "a_fighterquietus.cpp"
 #include "a_firedemon.cpp"
 #include "a_flechette.cpp"
+#include "a_flies.cpp"
 #include "a_fog.cpp"
 #include "a_healingradius.cpp"
 #include "a_heresiarch.cpp"

src/p_mobj.cpp

@@ -6236,11 +6236,11 @@ void AActor::Crash()
 	}
 }
 
-void AActor::SetIdle()
+void AActor::SetIdle(bool nofunction)
 {
 	FState *idle = FindState (NAME_Idle);
 	if (idle == NULL) idle = SpawnState;
-	SetState(idle);
+	SetState(idle, nofunction);
 }
 
 int AActor::SpawnHealth()

wadsrc/static/actors/hexen/flies.txt

@@ -0,0 +1,28 @@
+
+// Buzzy fly ----------------------------------------------------------------
+
+ACTOR LittleFly 112
+{
+	Game Hexen
+	+NOBLOCKMAP +NOGRAVITY
+	+CANPASS
+	
+	Speed 6
+	Radius 5
+	Height 5
+	Mass 2
+	ActiveSound "FlyBuzz"
+	
+	action native A_FlySearch();
+	action native A_FlyBuzz();
+	
+	States
+	{
+	Spawn:
+		TNT1 A 20 A_FlySearch	// [RH] Invisible when not flying
+		Loop
+	Buzz:
+		AFLY ABCD 3 A_FlyBuzz
+		Loop
+	}
+}

wadsrc/static/decorate.txt

@@ -93,6 +93,7 @@
 #include "actors/hexen/mageplayer.txt"
 #include "actors/hexen/pig.txt"
 #include "actors/hexen/flame.txt"
+#include "actors/hexen/flies.txt"
 #include "actors/hexen/hexenarmor.txt"
 #include "actors/hexen/hexendecorations.txt"
 #include "actors/hexen/hexenkeys.txt"

zdoom.vcproj

@@ -5228,6 +5228,42 @@
 						/>
 					</FileConfiguration>
 				</File>
+				<File
+					RelativePath=".\src\g_hexen\a_flies.cpp"
+					>
+					<FileConfiguration
+						Name="Release|Win32"
+						ExcludedFromBuild="true"
+						>
+						<Tool
+							Name="VCCLCompilerTool"
+						/>
+					</FileConfiguration>
+					<FileConfiguration
+						Name="Release|x64"
+						ExcludedFromBuild="true"
+						>
+						<Tool
+							Name="VCCLCompilerTool"
+						/>
+					</FileConfiguration>
+					<FileConfiguration
+						Name="Debug|Win32"
+						ExcludedFromBuild="true"
+						>
+						<Tool
+							Name="VCCLCompilerTool"
+						/>
+					</FileConfiguration>
+					<FileConfiguration
+						Name="Debug|x64"
+						ExcludedFromBuild="true"
+						>
+						<Tool
+							Name="VCCLCompilerTool"
+						/>
+					</FileConfiguration>
+				</File>
 				<File
 					RelativePath=".\src\g_hexen\a_fog.cpp"
 					>